Variable volume reversible hydraulic device



p 13, 1966 R. w. BRUNDAGE 3,272,128

VARIABLE VOLUME REVERSIBLE HYDRAULIC DEVICE Filed June 15, 1964 2 Sheets-Sheet 1 FIG. I

INVENTOR. ROBERT W BRUN DAGE fM a? ATTOR EYS p 1966 R. w. BRUNDAGE 3,272,128

VARIABLE VOLUME REVERSIBLE HYDRAULIC DEVICE Filed June 15, 1.964

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2 Sheets$heet 2 INVENTOR.

ROBERT W. BRUNDAGE EXAM f?! ATTORN S United States Patent 3,272,128 VARIABLE VQLUME REVERSIBLE HYDRAULIC DEVICE Robert W. Brundage, St. Louis, Mo, assignor to The Emerson Electric Company, St. Louis, Mo., a corporation of Missouri Filed June 15, 1964, Ser. No. 375,193 13 Claims. (Cl. 1ll33) This invention pertains to the art of hydraulic devices and more particularly to a variable-volume, or speed, reversible hydraulic device of the expanding and contracting chamber type.

The invention is particularly applicable to hydraulic pumps of the internal-external gear type and will be described with particular reference thereto although it will be appreciated that the invention, in many instances, is equally applicable to other types of pumps or motors of the type having continuously expanding or contracting chambers.

Such pumps include relatively movable members which define the chambers as they revolve on a closed path of movement. Manifold ports separated at the ends by lands communicate with the chambers as they revolve and supply or receive fluid to or from the chambers. These ports are then communicated externally of the pump.

This application describes in greater detail and claims certain features of the hydraulic pump shown and described in my co-pending application Serial No. 303,905, filed August 22, 1963.

In that application there is described and claimed a hydraulic laundry machine transmission including a onespeed, reversible electric motor driving a variable volume hydraulic pump which, depending upon its direction of rotation, supplies hydraulic fluid to either: a vane type oscillating motor for operating the agitator of a laundry machine; or a rotating, internal gear-type hydraulic motor for rotating the spin basket at high speeds.

In such laundry machines it is often desired to change the speed of agitation and/ or the speed of rotation of the spin basket, but usually it is desired to change the speed of the agitator While holding the speed of rotation of the spin basket relatively constant.

It is, of course, possible to vary the output volume of a hydraulic pump by bypassing through an external valve some of the output fluid back to inlet. However, the energy of the bypassed fluid is dissipated and this is undesirable.

It is also known to vary the output volume of a hydraulic pump by adjustably shifting both lands (and thus the manifold ports) of the pump away from their normal position on the neutral axis so that some of the decreasing volume chambers are communicated through one of the manifold ports with some of the increasing volume chambers and some of the other increasing volume chambers are communicated through another manifold port with some of the other decreasing volume chambers. With this arrangement, some of the hydraulic fluid being discharged at high pressure from the decreasing volume chambers then flows without drop in pressure internally of the pump through the manifold ports to the increasing volume chambers where the fluid under pressure gives up its energy by imparting a motor action to the pumping members. The net result is a decrease in the output volume of the pump but Without the energy loss of an external bypass. By shifting the lands to a position 90 from the neutral axis, the output volume can be reduced to zero.

With such an arrangement, approximately one-half of the chambers, whether decreasing or increasing in volume, are always at the high discharge pressure of the pump and the forces created by these pressures result in the same 3,272,128 Patented Sept. 13, 1966 loads on the pump bearings regardless of the output volume.

My Patent No. 2,898,862, issued August 11, 1959, overcame this problem by fixedly locating one of the lands on the neutral axis at the maximum volume point of the chambers and then adjustably shifting only the other land from its full volume position on the neutral axis at the minimum volume point of the chambers so that the land would be located at either increasing or decreasing volume chambers. This intercommunicated increasing and decreasing volume chambers and thus decreased the volume out-put of the chambers. Also, it decreased the bearing loads with the drop in volume output. To reduce the volume output to zero, the land had to be shifted through an arc of from its full volume position.

One of the problems with this arrangement is that the high pressure fluids constantly exert a force on the sides of the lands (i.e., on the end of the manifold port defined by the land) which force biases the land back to its mini mum volume position. This necessitated the use of means for lock-ing the land in any adjusted position.

The present invention deals with this problem and the member forming the movable land is always in hydraulic balance regardless of its adjusted position.

Hydraulic pumps, whether one or both lands are adjusted to vary the output volume, had the further difliculty that for a given degree of shift of the land or lands from the neutral axis, the change in volume output of the pump was the same for both directions of rotation of the pump.

The present invention deals with this problem by providing :an arrangement of the lands and manifold ports whereby, for the same angular shift of the land or lands, a greater range of change in the output volume will result for one direction of rotation than for the other direction of rotation.

In accordance with a principal aspect of the invention, a hydraulic device of the type described is provided having at least three manifold ports with lands at the ends thereof, one port communicating with chambers generally on one side of the neutral axis of the chambers and the other two ports each communicating with a portion of the chambers generally on the other side of the neutral axis. At least one of these two ports and its lands are relatively adjust-able relative to the other. When the device is a pump and discharging fluid through the two ports, adjustment of the one port relative to the other provides a greater volume change in the output of the pump than when the pump is rotating in the opposite direction and discharging fluid through the other first-mentioned port. Also, the member in which the port is formed and which forms the lands at the end thereof is in hydraulic balance.

In accordance with the invention, a hydraulic pump of the general type described is provided comprised of a plurality of manifold ports and lands therebetween so arrange-d that for the same adjustment of at least one manifold port and its associated lands relative to the other ports and lands, the change of volume output will be different dependent on the direction of rotation of the pump.

More specifically, in accordance with the invention, a hydraulic pump is provided comprised of: a plurality of rotatable members defining a plurality of pumping chambers which progressively increase in volume on one side of a neutral axis and decrease in volume on the other side as they revolve, and first and second manifold members. The first manifold member is fixed relative to the neutral axis and has first and second ports separated at the ends by lands. The first port is located generally on one side of the neutral axis and communicates with a major portion of all the chambers on that side of the axis. The second port is located generally on the other side of the neutral axis and communicates with only a portion of the chambers on that other side of the neutral axis. The second member is adjustable from a maximum volume position to a minimum volume position and has third and fourth ports separated at the ends by lands. In the maximum volume position, the third port is located on the same side of the neutral axis, as the first port and communicates with a major portion of the chambers on that side of the axis. The fourth port is located on the other side of the neutral axis and communicates with the other portion of the chambers on that side of the neutral axis. In the minimum volume position, the third port straddles the neutral axis to communicate chambers on both sides of the neutral axis and the fourth port overlaps and communicates with some of the chambers as the second port.

The second and fourth ports are intercommunicated externally of the pump. When the pump is rotating in a direction, to discharge fluid through the second and fourth port, adjustment of the movable member moves two lands which affects the output volume. When the pump is rotating in the opposite direction, fluid is discharged only from the first or third port. Adjustment of the movable member moves only one land. As the volume change is a function of the number of lands and the arc of movement, it is seen that the same movement of the member gives different volume changes.

In accordance with another aspect of the invention, the center of rotation of the adjustable member and the radially facing side walls of the ports therein are so related to the radially facing surfaces of the chambers that when the member is rotatably adjusted the amount of underlap of the ports to the chambers will change so as to maintain essentially the same pressure drop into and out of the chambers regardless of volume output.

In an alternative aspect of the invention, the manifold ports of the pump are adjustable circumferentially relative to the neutral axis of the pump so as to vary the pump output volume, with the manifold ports on each side of the axis being adjustable relative to pumping chambers having differing rates of volume change per degree of rotation such that the same circumferential adjustment of the ports produces one ratio of change in the output volume of the pump when the pump is rotating in one direction and a different ratio of change when rotating in the opposite direction. The ratio of maximum to minimum speeds of the two motors can thus be different.

The principal object of the invention is the provision of a new and improved variable volume hydraulic pump wherein the member for adjusting the volume output is always in hydraulic balance.

Another object of the invention is the provision of a new and improved variable volume hydraulic pump which, for the same degree of adjustment of the adjusting member, has different changes of volume output depending upon the direction of rotation.

Another object of the invention is the provision of a new and improved hydraulic pump wherein the volumetric efiiciency will remain approximately the same regardless of the adjustment of the output volume.

Another object of the invention is the provision of a new and improved variable volume hydraulic pump which is simple in construction, economical to manufacture and positive in its operation.

Another object of the invention is the provision of a new and improved variable volume hydraulic pump wherein the bearing loads decrease as the volume output decreases.

Another object of the invention is the provision of a new and improved variable volume hydraulic pump wherein the output of the pump is different depending upon the direction of rotation.

Still another object of the invention is the provision of a new and improved manifold for a hydraulic pump which increases the volumetric efiiciency.

The invention may take physical form in certain parts and arrangements of parts, a preferred embodiment of which will be hereinafter described in this specification in detail and illustrated in the accompanying drawings which form a part hereof and wherein:

FIGURE 1 is a side cross-sectional view of the pump portion of a hydraulic transmission illustrating a preferred embodiment of the present invention;

FIGURE 2 is a cross-sectional view of FIGURE 1 looking downwardly approximately on the line 22 thereof and showing in dotted lines the position of the lower manifold ports of the pump in relation to the hydraulic fluid conduits in the housing, the valve being shown in the neutral position;

FIGURE 3 is a cross-sectional view of FIGURE 1 taken approximately on the lines 3-3 thereof and also looking upwardly;

FIGURE 4 is a cross-sectional view of FIGURE 1 taken on the line 4-4 thereof which is the same line as 44 but looking downwardly; and with the passages of FIGURE 3 imposed thereon in dotted lines;

FIGURE 5 is a cross-sectional view of FIGURE 1 taken approximately on the line 55 thereof and in effect looking downwardly and showing the upper manifold port arrangement;

FIGURE 6 is a cross-sectional view of FIGURE 1 taken approximately on the line 66 thereof and showing the lower manifold port arrangement for the pump of the transmission, the gear teeth being superimposed thereon in dotted lines.

Referring now to the drawings, wherein the showings are for the purposes of illustrating a preferred embodiment of the invention only, and not for the purposes of limiting same, FIGURE 1 shows somewhat schematically a portion of the laundry machine transmission of application Serial No. 303,905, including a housing A and an electric motor B driving a hydraulic pump, comprised of pumping members C and an adjustable manifold plate D.

Valve means E within the housing A selectively controls the flow of fluid through suitable passages provided in the housing from the pump to either of two hydraulic motors, not shown.

Housing The housing A is comprised of two main pieces, an upper housing 15 and a lower housing 16 having lower and upper surfaces 15a, 16a respectively, which surfaces as will appear, have hydraulic inlet and discharge circuits as well as the valving surfaces for the valve E formed therein and which surfaces 15a, 16a are in tightly sealed engagement. These surfaces are cemented together although conventional bolts may be employed at an increase in size of the housing and increased cost.

A wall or flange 17 extends around the upper edge of the upper housing 15 and a cover plate 18 is held in sealing engagement with the upper edge of this flange by a plurality of fastening means, not shown, to form an oil reservoir or sump 20 for the pump.

The upper surface of the upper housing 15 on the left hand side is provided with a recess having a lower surface 42 and in which is positioned a steel sleeve 43a having an inner cylindrical surface 43. This recess is closed by a cap 45 and ported plate 47 having a lower surface 46 in sealing engagement with the upper surface of the housing 15 which cap 45 and plate 47 are suitably fastened to the housing by any suitable means, such as screws 48.

The cylindrical surface 43 has an axis parallel to but slightly offset from the axis of a shaft 50 extending upwardly through an opening in the lower housing 16 from the motor B.

Motor The motor B is the power source which powers the pump and may take any one of a number of known forms, and may be the single speed reversible type.

The lower surface of the lower housing member 16 is so shaped as to form the upper end bell of the motor B and the shaft 50, where it passes through the housing 16, is rotatably supported in a suitable bearing sleeve 60. An oil seal 61 is also provided.

The actual construction of the motor B forms no part of the present invention, it only being necessary for the embodiment of the invention shown that the motor B be readily reversible.

Pumping members The pumping members C may take a number of differout forms wherein they form pumping chambers which rotate or revolve on a closed path of movement and progressively increase and decrease in volume as they rotate, e.g., a reciprocating piston type pump, a rotating vane type pump, or the like; but in the preferred embodiment, an internal external gear type pump is employed comprised of an externally toothed gear 62 keyed to the shaft 51 by means of a key 63 and an internally toothed ring gear 64 rotatably supported by the cylindrical surface 43 on an axis slightly spaced from that of the gear 62. As is conventional, the ring gear 64 has one (or more) tooth more than the internal gear 62 and the teeth of these gears are in sliding sealing engagement to provide a plurality of pumping chambers which progressively increase in volume after they pass the minimum volume point 7 a (FIGURES 5, 6) on a neutral axis 70 to a point 70b of maximum volume on the neutral axis 70, and then progressively decrease in volume until they reach the minimum volume point 70a. Hydraulic fluid is thus sucked into and forced out of these chambers, depending on whether the volume is increasing or decreasing.

Fixed manifold ports and lands In accordance with the invention, the pump has two separate members forming its manifold ports and lands. One member is fixed, the other adjustable. In the embodiment shown the fixed member is the housing A. Thus the lower surface 42 of the pump cavity has three manifold ports 66, 67, 68 (FIGURE 6) formed therein which communicate with passages 66a, 67a, 68a respectively formed in the abutting surfaces of the housing members 15, 16. These manifold ports 66, 67, 68 are generally arcuate and are positioned a distance from the axis of the shaft 50 such as to communicate with the chambers of the gears 62, 64 as they rotate. The arcuate ends of the manifolds 66, 67, 68 are circumferentially spaced from each other so that the surface 42 between the ends of ports forms the pump lands 42a, 42b, 420, it being noted that the entire surface 42 (and these lands) is in sliding sealing engagement with the lower surfaces of the gears 62, 64 to thus seal the chambers, one from the other, except where by virtue of a manifold port overlapping one or more chambers, they are in communication.

The arcuate lands or angular extent of each manifold port and the lands between the ports is largely determined by the arcuate length or angular width of each pumping chamber defined by the gear teeth of the gear 62, 64. In the preferred embodiment, the externally toothed gear 62 has eight teeth and the internally toothed gear 64 has nine teeth which define eight pumping chambers, half of which (on one side of the neutral axis) are increasing in volume and the other half (on the opposite side of the neutral axis) are decreasing in volume. Each chamber has an arcuate extent of approximately 45. For a land to prevent communication from the high pressure to the low pressure through a pumping chamber, it must have an arcuate extent of approximately 90. The exact angle depends on the gears used. Anything under this exact angle results in trapping or cavitation, namely, a moment in the arc of rotation when fluid cannot escape from or flow into a pumping chamber as it is changing its volume. While both are to be avoided, trapping is the more detrimental of the two because the pressures in a decreasing volume chamber can momentarily increase to very high values if the fluid for even a moment is prevented from being discharged from a decreasing volume chamber.

The lands of a hydraulic pump are normally located on the neutral axis. In the preferred embodiment shown, however, and for reasons as explained in my Patent No. 3,007,418, issued November 7, 1961, the lands (and thus the manifold ports) are shifted from the neutral axis by a predetermined amount. One land is made narrower than the exact angle above referred to prevent trapping or cavitation while the other land is made much wider than the exact angle and is then provided with a trapping port.

Thus, land 42c has an arcuate extent just less than 90 and its center line is shifted approximately 45 from the minimum volume point of the neutral axis.

Lands 42a and 42b are in effect a single land separated by a trapping port 68 which, as heretofore pointed out, communicates with the sump. The total width of the lands 42a and 42b, including the width of the trapping port, is approximate-1y 120.

Port 67 has an arcuate length just in excess of 90 while port 66 has an arcuate length of approximately 60. These ports taper in radial width as shown toward the minimum volume point of the chambers. Port 68 is relatively narrow and is located approximately on the open mesh point of the neutral axis.

It is to be further noted that the circumferential ends of the ports 66 and 67, that is to say, the sides of the lands 42a, 42b, and 420 are generally flat (except for the radius at the end), and is located generally on a radial line through the axis of rotation of the gears 62, 64.

Ad iustable manifold The second set of manifold ports are located in the adjustable manifold plate D located on top of the gears 62, 64. This plate D has a lower surface 73, in sealing engagement with the upper surface of the gears 62, 64 and an upper surface in sealing engagement with the lower surface of ported plate 47. This manifold plate 72 has (FIGURE 5) three arcuate manifold ports 75, 76, 77 extending therethrough; and the ends are respectively separated by portions of the surface 73, which may be called lands 73a, 73b, 730; the ports being spaced from the axis of rotation of the shaft 50, such that they communicate with the chambers of the gears 62, 64 as they revolve. The surface 73 (and the lands) is in sliding sealing engagement with the upper surface of gears 62, 64.

The manifold plate D is mounted for rotation through a limited are about an axis 79 which, in accordance with the invention, is offset from both aXes of rotation of the gears 62, 64 a short distance on the neutral axis towards the minimum volume point 70a, of the gears for reasons which will appear hereinafter:

The are of movement of the manifold plate 72 is limited by a tab 80 on the plate D extending into an arcuate recess 81 in the housing and having circumferential ends which the tab 80 engages at either end of the arc of movement of the manifold plate D. As will appear, rotation of this manifold plate D varies the output volume of the pump per revolution.

A control shaft 83 rotatable on axis 79 in a vertical opening in the cap 45 and having a rectangular lower end 84 fits into a correspondingly shaped opening in the manifold plate D so that this plate may be readily rotated. An O-ring 85 seals this shaft where it passes through the cap 45. The shaft 83 passes through an opening 86 in the cover plate 18. The cover plate 18 around this opening 86 is sealed to the upper surface of the cap 45 by a seal 88. Any suitable control means may be connected to the exposed end of the shaft 83.

Manifold port 75 at all positions of the manifold plate 72 is in communication with passage 75a in the abutting surfaces of the two housing members 15, 16 through a port 75b in the ported plate 47, groove 750 in the lower surface of cap 45 and a vertical passage 75d in the upper housing. Passage 75a in turn communicates with passage 6611 so that ports 75 and 66 are always intercommunicated externally of the pump.

In the maximum volume counterclockwise position of plate 72, manifold port 76 is communicated with the pump or oil reservoir through port 76a in plate 47, and a radial groove 76b in the lower surface of cap which extends beyond the side of the housing 15 and is open to the sump 20.

It is to be noted that the manifold port 77 does not communicate with any passage in the housing. Its sole function is to communicate decreasing volume chambers with increasing volume chambers when the plate 72 is adjusted clockwise to positions for less than the maximum volume output of the pump.

Manifold port 62 has an arcuate extent of approximate- 1y 180 and is shiftable from a position (not shown) where it communicates with generally all of the chambers on one side of the neutral axis, namely, the side with which the manifold port 67 communicates, to a position as is shown in FIGURE 6 where it communicates with some of the chambers on the other side of the neutral axis.

Land 730, when in a maximum volume counterclockwise position (not shown), is located approximately on the neutral axis and has an angular width somewhat less than the angular width of the pumping chambers. Thus, in all positions of the manifold plate D, fluid from a decreasing volume chamber can flow around the land 730 into an increasing volume chamber. It is to be noted that in the minimum volume position shown in FIG- URE 5, the center line of land 73c is approximately aligned with the center line of land 420.

Port 75 has an arcuate extent of approximately the same as that of port 66 and it is to be noted that in the maximum volume counterclockwise position of the manifold plate D, the ports and 66 combined have an arcuate extent of approximately Port 76 serves as a trapping port between lands 73a and 73b and as indicated, this port communicates atall times with the sump.

It is to be further noted that ports 75 and 77 have a maximum radial width at the maximum volume chamber end and decreases gradually toward the minimum chamber volume end. Port 77 at the minimum chamber volume end is offset radially outwardly a small amount as is shown in FIGURE 5.

In accordance with the invention, the radial facing surface We of 77 of port 77 have a center of curvature corresponding to the center of rotation of the manifold plate D and a radius such that in the minimum volume position shown in FIGURE 5, the surfaces will slightly overlap the radial facing surfaces of the chambers, that is to say, they will be positioned outwardly beyond the roots of the gear teeth. This in part restricts the free flow of fluid into and out of these chambers. As heretofore pointed out, the center of rotation of the manifold plate D is offset on the neutral axis toward the minimum volume chamber such that when the plate D is rotated from the position shown in FIGURE 6, the inner surfaces 772 and 771] will move radially inwardly relative to the roots of the gears and will no longer restrict the flow of fluid into and out of these chambers. With this arrangement, a more uniform pressure drop into and out of these chambers will be maintained regardless of the volume output. In the event this aspect of the invention is used with a ported plate, then the radially facing surfaces of the chambers would be the radially facing surfaces of the ports in the plate.

Operation Assuming the manifold plate D to be in the full volume position, when the gears are rotating in the counterclockwise direction, fluid is discharged outwardly through both the ports 66 and 75. When the gears are rotating in the clockwise direction, fluid is discharged both into Cir the manifold port 67 and the manifold port 77. Manifold port 77, however, does not have a passage in the housing leading therefrom and fluid which is discharged into port 77 flows circumferentially to the end and thence axially through the gear chambers to the manifold port 67. The full discharge volume of the pump thus flows into the manifold port 67.

The ratio of fluid pumped for either direction of rotation is thus one.

When the manifold plate 72 is rotated to the reduced volume position shown in FIGURE 6, a different situation prevails. In the clockwise direction of rotation, the land 73a has closed off a segment of the decreasing volume chambers from communication with the port 77 and thus the port 67. This, in part, cuts down the output. Port 77 communicates the decreasing volume chambers which would normally be closed in this position of plate 72 by lands 73a, 73b and 42a with port 68 and prevents trapping of fluid therein.

At the same time, land 73c has moved so that port 77 communicates some of the increasing volume chambers with some of the decreasing volume chambers. Fluid from these decreasing volume chambers flows into these increasing volume chambers and because it is under high pressure, exerts a motor action and its energy is recovered. This fluid does not appear in the output.

When the pump is rotating in the counterclockwise direction, rotation of the land 73c over the decreasing volume chambers reduces the output volume of the pump because the fluid being discharged from these decreasing volume chambers now in communication with the clockwise end of the manifold port 77 flows through the port into the increasing volume chambers. This fluid is lost to the output. The movement of land 7311 has no effect on the output volume. It simply allows ports 75 and 76 to overlap in an axial direction.

It is to be noted that when the pump is rotating in the counterclockwise direction, there are in actuality two discharge ports (which are intercommunicated remote from the ports) and one inlet port at all times. However, when the pump is rotating in the clockwise direction, there is one discharge port and two inlet ports. In effect, the pump is triple ported.

With such triple porting, when the pump is rotating in the clockwise direction, and the manifold member 72 is adjusted to decrease the output volume of the pump, two lands affecting the output volume are moved. However, when the pump is rotating in the counterclockwise spin direction, only one land affecting the output volume is moved. As the volume change is proportional to the arc of adjustment of the lands and the number of lands which adjust the change in volume for the same angular adjustment of the plate D is greater for agitate than for spin.

This same result could be obtained by triple porting the pump and directing the flow of one of the smaller ports to the sump by means of a valve when the pump rotates in one direction. It is to be noted that as the member actually has two lands it is always in hydraulic balance.

Likewise, this same differential adjustment of the output volume depending upon the direction of rotation of the pump may be obtained by utilizing the non-linear rate of discharge from each chamber as it moves from the point of maximum volume to the point of minimum volume. Thus, in an internal gear type pump of the type described, the output of the pump varies along the cosine curve as one of the seal lands of the manifold is rotated from the maximum position on the neutral axis. This results in relatively little change in volume for each degree of movement of a land as the land is started to be moved from the neutral axis which change in volume per degree of movement progressively increases as the angle of the land from the neutral axis approaches The adjustable manifold member may have three unequally spaced lands dividing the adjustable manifold into three distinct ports (at the maximum volume position): the first, an outlet port on a first direction of rotation, and inlet on the second direction; the second an inlet port on first direction and an outlet port to the sump on the second direction, and the third, an inlet port on the first direction and an outlet port on the second direction. With this arrangement the lands affecting the volume output on the first direction are different than those affecting the output on the second direction and at least one of the latter moves over the arc of movement of the chambers more remote from the neutral axes than the former.

In the embodiment of the invention shown, it has been possible to obtain output volume variations on one direction of rotation of approximately two to one and on the second direction of rotation two to one and one-half.

This is desirable where the pump is used in a laundry machine transmission because in washing clothes it is sometimes desirable with delicate clothing to reduce the speed of agitation to prevent damage to the clothes. However, for the same fragile clothes, it is not as necessary to reduce the spin speed.

The preferred embodiment of the invention has been described in great detail sufiicient to enable one skilled in the art of hydraulics and mechanics to duplicate the invention. Obviously, modifications and alterations of the preferred embodiment described will occur to others upon a reading and understanding of this specification and it is my intention to include all such modifications and alterations as part of my invention insofar as they come within the scope of the appended claims.

Having thus described my invention, I claim:

1. In a variable volume hydraulic pump comprised of a plurality of relatively movable members defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, the improvement which comprises; said means including a first member fixed relative to said neutral axis and having at least a pair of manifold ports communicating with a portion of said chambers and a second member movable from a maximum volume to a minimum volume position and having at least a manifold port which in the maximum volume position of said second member communicates with another portion of said chambers, said second member manifold port when said second member is moved from said maximum volume position communicating with at least a part of the chambers with which the manifold ports of said first member communicate.

2. In a variable volume hydraulic pump comprised of a plurality of relatively movable members defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, the improvement which comprises; said means including first and second members, said first member being fixed relative to said neutral axis and having at least a first and second manifold port, saidfirst manifold port communicating generally with one half of said chambers, said second manifold port communicating generally with one-fourth of said chambers, said second member being movable from a maximum volume position to a minimum volume position and having at least a third manifold port, said third manifold port communicating in a maximum volume position generally with the remaining one-fourth of said chambers, and in the minimum volume position communicating with at least some of the chambers with which said second manifold port communicates and means communicating all of said ports externally of said pump.

3. The improvement of claim 2 wherein said second member has a fourth port which in the maximum volume position communicates generally with the chambers with which said first manifold port communicates and in a minimum volume position communicates with a portion of chambers with which said first manifold port communicates and with at least a portion of the chambers with which said third manifold port communicated when said second member was in the maximum volume position.

4. In a variable volume hydraulic pump comprised of a plurality of relatively movable members defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, the improvement which comprises; said means comprising a first member fixed relative to said neutral axis and having a pair of manifold ports and a second member movable from a maximum volume position to a minimum volume position and having a manifold port, said ports being so arranged that when the second member is in the minimum volume position the output volume of the pump is less for one direction of rotation than for the opposite direction of rotation.

5. In a variable volume hydraulic pump comprised of a plurality of relatively movable members defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, the improvement which comprises; said means including a first member fixed relative to said neutral axis and having at least first and second manifold ports, said first manifold port communicating with chambers generally on one side of said neutral axis, said second manifold port communicating with a portion of the chambers generally on the opposite side of said neutral axis, said second member being movable from a maximum volume position to a minimum volume position and having a third port which in the maximum volume position communicates with another portion of the chambers on the said side of the neutral axis as the chambers in communication with the second port, said third manifold port when the second member is in a minimum volume position communicating with a portion of the chambers with which said second manifold port communicates.

6. The improvement of claim 5, wherein said second member has a fourth manifold port which in the maximu volume position communicates (with the chambers on the same side as the first manifold port and in the minimum volume position communicates with some of the chambers with which the first manifold port communicates and some of the chambers with which the third manifold port communicated in the maximum volume position of the second member.

7. In a variable volume hydraulic pump comprised of a plurality of relatively movable members defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, said openings from said chambers having radially facing sidewalls which move on a circle having a predetermined center, the improvement which comprises; a manifold member rotatable from a maximum volume position to a minimum volume position, said manifold member having at least a pair of manifold ports therethrough having radially facing inner and outer sidewalls, said manifold member being rotatable about an axis spaced from said center whereby said manifold ports move radially relative to the line of movement of said openings when said manifold member is adjusted from the maximum volume position to the minimum volume position.

8. In a variable volume hydraulic pump comprised of a plurality of relatively movable members defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, said openings being of a predetermined radial width, and moving on a closed path of movement having a predetermined center, the improvement which comprises; an adjustable manifold member rotatable about an axis from a maximum volume position to a minimum volume position, said manifold member having at least a pair of manifold ports having a predetermined radial width approximately the same as the radial width of said openings, said axis of rotation of the manifold member being spaced from the center of rotation of the openings whereby the radial alignment of the manifold ports with the opening shifts as said manifold member is moved from maximum volume position to minimum volume position.

9. In a variable volume hydraulic pump comprised of a plurality of relatively movable members defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, said openings having a predetermined radial width and moving on a generally circular path of movement having a predetermined center of rotation, the improvement which comprises said means defining said manifold ports including a first and second member, said first member being fixed relative to said neutral axis and having at least first and second manifold ports, said first manifold port communicating generally with the chambers on one side of the neutral axis, said second manifold port communicating generally with a portion of the chambers on the other side of the neutral axis, said second member being movable from a maximum volume position to a minimum volume position and having third and fourth manifold ports, said third manifold port in the maximum volume position communicating generally with the other portion of the chambers on the same side of the neutral axis as the second manifold port, said fourth manifold port in the maximum volume position communicating generally with chambers on the same side of the neutral axis as the first manifold port, said third and fourth manifold port having a radial width approximately the same as the radial width of said openings and having arcuate sidewalls generally having a center of curvature approximately corresponding with the center of rotation of said second member, said center of rotation being spaced from the center of rotation of said openings on the neutral axis toward the minimum volume point of the chamber.

10. In a variable volume hydraulic pump comprised of a plurality of relatively movable members defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, a first member being fixed relative to said neutral axis and having first and second manifold ports and means communicating said ports externally of said pump, said first member having a minimum volume land and a maximum volume land located generally on the neutral axis, said minimum volume land being shifted from said neutral axis and having a circumferential width approximately the same as the circumferential spacing between the centers of said openings, said maximum volume land having a circumferential width greater than the circumferential spacing between said openings, said last mentioned land having a trapping port communicating with the sump, a second member movable from the maximum volume position to a minimum volume position and having a third and fourth manifold port, means communicating the third manifold port externally of said pump, means closing the fourth manifold port, said ports being separated at the ends by lands, one of the lands in the maximum volume position being located generally on the neutral axis of the minimum volume point of the chambers and the other land at the maximum volume position being located generally on the neutral axis at the maximum volume point of the chambers, said first mentioned land of said second member having a circumferential width less than the circumferential spacing between the centers of said openings, said last mentioned land as such second member in the maximum volume position having a circumferential width greater than the circumferential spacing of said openings and a trapping port through said last mentioned land and means communicating said port with a sump.

11. In a variable volume hydraulic pump comprised of: a housing, a plurality of relatively movable members in said housing defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, said housing being fixed relative to said axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, the improvement which comprises; an adjustable manifold member movable from a maximum volume position to a minimum volume position, said manifold member including at least first, second and third manifold ports, said first manifold port communicating generally with one half of said chambers, means communicating said first manifold port externally of said pump, said second manifold port communicating with a portion of said chambers, means communicating said second manifold port externally of said pump, said third manifold port being of a lesser circumferential width, and means communicating said third port with a sump.

12. In a variable volume hydraulic pump comprised of: a housing, a plurality of relatively movable members in said housing defining a plurality of chambers which revolve about a common center and continuously expand in volume on one side of a neutral axis and continuously contract in volume on the other side of the neutral axis, means defining a plurality of manifold ports separated at the ends by lands, said chambers having openings which move past said lands and consecutively communicate with said manifold ports, the improvement which comprises; said means defining said manifold ports including a manifold member in said housing adjustable relative to said axis and having at least a first, second, and third manifold port, said first manifold port communicating generally with chambers on one side of said neutral axis, said second manifold port communicating generally with chambers on the other side of said neutral axis, one of said ports being at high hydraulic pressure, the other of said ports being at sump pressure, said third manifold port being located generally on the neutral axis at the maximum volume point of the chambers, and means communicating said third manifold port with the sump, said manifold member being movable from a maximum volume position to a minimum volume position.

13. In a variable volume hydraulic pump comprised of an internally toothed and an externally toothed gear rotatable about axes and defining a plurality of chambers Which revolve about a common center continuously expand on one side of a neutral axis and continuously contract on the other side of the neutral axis, means on both axial sides of said gears defining manifold ports separated at the ends by lands, said chambers having openings at both axial ends which move past said lands and consecutively communicate with said manifold ports, the improvement which comprises a first manifold member fixed relative to said neutral axis and in sealing engagement With one axial end of said gears and having a pair of manifold ports therein, a second manifold member in sealing engagement With the other axial end of said gears and having a pair of manifold ports therethrough, said second member being adjustable from a maximum volume position to a minimum volume position.

References Cited by the Examiner UNITED STATES PATENTS 2,569,717 10/1951 Hall 1033 2,847,938 8/1958 Gondels 103-162 2,899,903 8/1959 Ryder 103120 2,948,229 8/1960 Brundage 103-120 3,045,778 7/1962 Mosbacher 1046 3,106,897 10/1963 Johnson 103-120 3,120,814 2/1964 Mueller 103-120 3,128,707 4/1964 Brundage 103-2 3,137,234 6/1964 Mosbacher 1032 3,160,104 12/1964 Barnard 103-41 3,175,508 3/1965 Smithson 103162 MARK NEWMAN, Primary Examiner. SAMUEL LEVINE, Examiner.

W. L. FREEH, Assistant Examiner. 

1. IN A VARIABLE VOLUME HYDRAULIC PUMP COMPRISED OF A PLURALITY OF RELATIVELY MOVABLE MEMBERS DEFINING A PLURALITY OF CHAMBERS WHICH REVOLVE ABOUT A COMMON CENTER AND CONTINUOUSLY EXPAND IN VOLUME ON ONE SIDE OF A NEUTRAL AXIS AND CONTINUOUSLY CONTRACT IN VOLUME ON THE OTHER SIDE OF THE NEUTRAL AXIS, MEANS DEFINING A PLURALITY OF MANIFOLD PORTS SEPARATED AT THE ENDS BY LANDS, SAID CHAMBERS HAVING OPENINGS WHICH MOVE PAST SAID LANDS AND CONSECUTIVELY COMMUNICATE WITH SAID MANIFOLD PORTS, THE IMPROVEMENT WHICH COMPRISES; SAID MEANS INCLUDING A FIRST MEMBER FIXED RELATIVE TO SAID NEUTRAL AXIS AND HAVING AT LEAST A PAIR OF MANIFOLD PORTS COMMUNICATING WITH A PORTION OF SAID CHAMBERS AND A SECOND MEMBER MOVABLE FROM A MAXIMUM VOLUME TO A MINIMUM VOLUME POSITION AND HAVING AT LEAST A MANIFOLD PORT WHICH IN THE MAXIMUM VOLUME POSITION OF SAID SECOND MEMBER COMMUNICATES WITH ANOTHER PORTION OF SAID CHAMBERS, SAID SECOND MEMBER MANIFOLD PORT WHEN SAID SECOND MEMBER IS MOVED FROM SAID MAXIMUM VOLUME POSITION COMMUNICATING WITH AT LEAST A PART OF THE CHAMBERS WITH WHICH THE MANIFOLD PORTS OF SAID FIRST MEMBER COMMUNICATE. 